Serial Attached SCSI (SAS) is a storage interface suitable for providing full-duplex high speed communication. In a typical SAS RAID environment, redundant SAS RAID controllers reside within a single storage enclosure. In these instances, damage or failure of the RAID controller may require repair or replacement before operation of the storage subsystem can resume. Further, while the RAID array may provide redundancy for the data, damage or failure of other components within the subsystem may render data storage and access unavailable. Additionally, RAID controllers within a subsystem may be vulnerable to subsystem level failures such as localized damage, cable failure, power surges, and the like which affect only the subsystem. Thus, it may be desirable to house individual SAS RAID controllers in separate storage subsystems. However, interconnection of controllers across separate subsystems in a SAS environment requires consideration of routing and address mapping restrictions for providing interconnection for end devices. Specifically, a system providing a robust, redundant intercontroller connection between two or more controllers that does not violate basic SAS expander device routing and address mapping restrictions is necessary.
Consequently, it would be advantageous if a system and method existed for providing interconnection of SAS RAID controller devices across redundant storage subsystems.